Drug resistance hampers fight against tuberculosis

LONDON (Reuters) - Rising rates of multi-drug resistant tuberculosis (TB) are hampering world health programs aimed at tackling TB and threaten to wipe out progress made against the disease, scientists said on Friday.

Experts from the World Health Organization and the European Center for Disease Prevention and Control (ECDC) said they were concerned about spreading multidrug-resistant TB, known as MDR TB, in Europe, and the persistence of TB among children.

A second report, in The Lancet medical journal, said sub-Saharan Africa was disproportionately affected and accounted for four of every five cases of tuberculosis linked to HIV, the human immunodeficiency virus that causes AIDS.

"Increasing rates of drug-resistant TB in eastern Europe, Asia, and sub-Saharan Africa now threaten to undermine the gains made by worldwide tuberculosis control programs," said researchers in The Lancet.

TB kills an estimated 1.7 million people each year and the worldwide number of new cases -- more than 9 million -- is higher than at any other time in history, they said.

According to data from the WHO's European office, reported rates of TB have been falling in Europe since 2005 with a regional average of 36.8 notifications per 100,000 population in 2009. But notification rates of newly detected and relapsed TB cases in 18 high-priority countries remain almost eight times higher than in the rest of the region, the WHO data show.

"Vulnerable populations, including children, still do not have ready access to quality and timely diagnosis and treatment," the WHO-ECDC report said. "This remains a matter of urgency given the high prevalence of multi- and extensively drug-resistant TB in the region.

Up to a third of people worldwide are infected with the bacterium that causes TB, but only a small percentage ever develop the disease. Studies show that people with substance abuse problems, those who are poor and those who live in hard-to-reach communities are more prone to the disease.

The AIDS epidemic drove up the number of TB cases across the world in the late 1980s and 1990s because the immune suppression caused by HIV can make a person far more susceptible to TB.

People can get drug-resistant forms of TB either as a result of catching such a strain from another person or because of inappropriate or incomplete treatment.

In The Lancet report, Alimuddin Zumla of University College London Medical School and Stephen Lawn of the University of Cape Town said rising global rates of diabetes and high rates of smoking in low and middle-income countries were now increasingly important drivers of the TB epidemic.

Diabetes raises the risk of developing TB three-fold and smoking increases it two-fold, they said.

The experts concluded that progress toward controlling TB worldwide was being hampered by an absence of a quick and cheap diagnostic test, the long duration of treatment, the lack of an effective vaccine, rising rates of drug-resistant TB and weak health systems in developing countries.